Be defensive with File.listFiles()

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/archive/ExplodedArchive.java

@@ -85,7 +85,11 @@ public class ExplodedArchive extends Archive {
 			this.entries.put(entry.getName(), entry);
 		}
 		if (file.isDirectory()) {
-			for (File child : file.listFiles()) {
+			File[] files = file.listFiles();
+			if (files == null) {
+				return;
+			}
+			for (File child : files) {
 				if (!SKIPPED_NAMES.contains(child.getName())) {
 					if (file.equals(this.root) || this.recursive) {
 						buildEntries(child);

spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/archive/SpecialArchiveTests.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2012-2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.loader.archive;
+
+import java.io.File;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.junit.Test;
+
+import static org.hamcrest.Matchers.greaterThan;
+import static org.junit.Assert.assertThat;
+
+/**
+ * @author Dave Syer
+ */
+public class SpecialArchiveTests {
+
+	@Test
+	public void getEntriesForRoot() throws Exception {
+		ExplodedArchive archive = new ExplodedArchive(new File("/"), false);
+		Map<String, Archive.Entry> entries = getEntriesMap(archive);
+		assertThat(entries.size(), greaterThan(1));
+	}
+
+	private Map<String, Archive.Entry> getEntriesMap(Archive archive) {
+		Map<String, Archive.Entry> entries = new HashMap<String, Archive.Entry>();
+		for (Archive.Entry entry : archive.getEntries()) {
+			entries.put(entry.getName().toString(), entry);
+		}
+		return entries;
+	}
+}